Approaching Coupled Cluster Accuracy with Density Functional Theory Using the Generalized Connectivity-Based...

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Chemistry

Background:

• The Pople isodesmic bond separation scheme is a foundational method for calculating molecular energies.
• Accurate computational chemistry often requires computationally expensive high-level methods.
• Density Functional Theory (DFT) methods can suffer from systematic errors due to approximations.

Purpose of the Study:

• To review the Connectivity-based Hierarchy (CBH) method for achieving chemical accuracy.
• To demonstrate CBH's applicability to a wide range of organic and biomolecular systems.
• To showcase CBH's ability to yield accurate results irrespective of the DFT functional used.

Main Methods:

• Generalization of Pople's isodesmic scheme using molecular structure and connectivity.
• Formulation as a series of rungs with increasing error cancellation on molecular fragments.
• Application of CBH to diverse chemical problems including reaction energies, bond energies, redox potentials, and pKa.

Main Results:

• Near-chemical accuracy (1-2 kcal/mol) achieved across various applications using DFT.
• CBH effectively corrects systematic errors in small molecular fragments.
• The method provides coupled cluster accuracy at the computational cost of DFT.

Conclusions:

• CBH offers a cost-effective route to highly accurate computational chemistry predictions.
• The systematic correction of errors in local fragments is key to CBH's success.
• CBH is a versatile tool applicable to complex organic and biomolecular systems.